Added headers & defaultHeaders source param
Added headers & defaultHeaders source param

Overrides the headers that source.getTile() returns

kartotherian/kartotherian,kartotherian/kartotherian-core,kartotherian/kartotherian,kartotherian/core,nyurik/kartotherian,nyurik/kartotherian,kartotherian/kartotherian,nyurik/kartotherian,nyurik/kartotherian,kartotherian/kartotherian